Truculently is the adverb: doing something in an aggressive, argumentative, defiant way. It goes with verbs of speaking and behaving, because truculence lives in how you deliver something — "he answered truculently", "she stared truculently at the floor", "'Make me,' he said truculently." Notice how often it appears in stories right after a piece of dialogue. That is its natural home. A writer uses it to tell you the exact temperature of a line that, written on the page, could have been read several ways: the words say one thing, and *truculently* tells you they were fired like a challenge. Formal and literary; almost nobody says it out loud in conversation. Position is flexible — after the verb ("he replied truculently") or before it ("he truculently refused") — but after the verb is more common and reads more naturally.